Oil booms are vertical skirts which are placed in water bodies to contain oil or hazardous materials such as gasoline, and prevent these materials from causing environmental damage to areas such as the environmental damage caused by the Exxon VALDEZ in the Prince William Sound. As illustrated in FIG. 1, an oil boom 10 includes a floatation chamber 12, which suspends a vertical boom draft skirt 14, wherein the floatation chamber 12 provides freeboard above the water surface and the boom skirt 14 provides draft below the water surface. A chain or ballast weight 16 is also connected to the lower end of the boom skirt in order to maintain the boom skirt in a vertical position.
As illustrated in FIG. 2, oil booms may be towed in either "J", "U", or "V", configurations or can be anchored in stationary positions (the "O" configuration) around vessels or in a manner to protect an environmentally sensitive shore line. Oil booms typically are produced in lengths of 50 or 100 feet, wherein a given length of boom is connected to an identical length of boom or a towing assembly via a connector. Interconnection between boom sections can be provided with the various jaw configurations by mating two connectors together or mating boom sections to a towing hawser. Typical jaw configurations are defined by the American Society for Testing and Materials (ASTM) and also by industrial configurations.
Oil boom connectors presently utilized in industry come in a variety of shapes. Typically, connectors include two flat plates bolted through a fabric member, wherein a connecting jaw or other connecting interface is utilized to mate two connectors at the junction of the two boom sections. A typical flat plate-bolted assembly is illustrated in FIG. 3(g). As discussed above, however, there are numerous oil boom connectors in various shapes, with various advantages and disadvantages. A good oil boom connector must be secure, strong, and prevent oil leaks. Connector strength is a primary consideration because failure of the oil boom is often at the connector.
In addition to the basic connector requirements of security, strength, and oil leak prevention, a connector should also be easy to manipulate. This is particularly important if boom sections are stored separately. If the connectors are difficult to manipulate, it may be necessary to lay the boom out in joint sections before it is deployed. In many spill situations, there is not enough working space to lay the boom out or if there is space, rough weather may make joining the sections difficult.
Further, sometimes boom skirts of different lengths are required after the boom is in the water. In order to change the boom skirt, boat crewman must lean over the side, draw two ends together, and make the connection. This task may be difficult in strong current, high winds, stormy seas, and low temperatures. Reports from the Prince William Sound during the VALDEZ spill revealed that even universal ASTM connectors are difficult to hook up, especially when the booms are in tension. Further, in cold water, variable rates of expansion of aluminum and stainless steel parts make connectors difficult to open. If the boom skirt must be changed after the oil boom has been deployed, a connector is required which can be quickly joined by a crewman working out of a boat, without the use of tools or requiring manipulation of loose bolts, pins, or cover plates. Complicated attachments involving loose fasteners generally can not be made from a pitching boat in rough water. In addition, loose bolts and tools are likely to be lost over the side of the vessel. Ideally, boom connectors should have the following features:
1) sections can be joined by simply drawing the two ends together;
2) any two ends can be joined, i.e., there are no male and female attachments;
3) connectors can be secured by simply turning a wing nut or inserting a pin and boom sections can be joined in a few minutes by men working from a small boat in rough weather;
4) connectors continue to be operable even when covered with some ice; and
5) connectors can be manipulated in cold weather by crewman wearing heavy gloves.
FIGS. 3(a) to (i) illustrate most types of connectors currently available. The first type illustrated in FIG. 3(a) is a quick connector. These "Z" type fittings are joined and secured with a wing nut or pin.
The second type, illustrated in FIG. 3(b), is a universal slide type 1 connector. This is similar to the quick connector except that the two ends must slide together either from the top or the bottom. The term "universal" is used because there are no male or female connections. FIG. 3(c) illustrates a universal slide type 2 connector. FIG. 3(d) illustrates a slide type connector which has a male and female attachment on opposite ends of the boom.
FIG. 3(e) illustrates a slotted tube connector, wherein a plastic slotted tube slides over a sealed rope at each end of the boom. The slotted tube end connector does not have male or female connections. FIG. 3(f) illustrates a raised channel connector, wherein one end of the boom has a raised channel similar to the slotted tube, while the other end has a raised fabric that is pulled through the tube. As is illustrated in FIG. 3(f), there is a male and female end.
FIG. 3(g) illustrates a bolt connector, wherein bolts are inserted through matching holes in the fabric on both ends of the boom and secured with simple nuts or wing nuts. Further, the front and back of the sections to be joined are reinforced with a metal plate.
As illustrated in FIG. 3(h), a hinged plate and pin end connector has a flat plate on each end of the boom. A male end has a fixed pin at the top and a hole at the bottom and a female end has a slot at the top and a hole at the bottom. The slot is aligned over the fixed pins then the holes in both ends are matched up at the bottom and secured with a separate pin.
Finally, the hinge and pin end connector illustrated in FIG. 3(i) is a simple "piano" hinge with a long pin that is inserted through the joint ends.
Some advantages and disadvantages of the various connectors discussed above is apparent from the above description and FIGS. 3(a) to (i). Other advantages and disadvantages are not readily apparent. Each of the above illustrated end connectors will be discussed in further detail below.
Quick connectors are easy to join as the name implies, generally by one person, and probably from a boat in some kind of adverse weather. No tools are required, locking pins are attached with a lanyard and can not be lost over the side of the boat, and there are no problems with male and female connectors if they are rigged properly. In heavy seas, there could be some problem lining up the two ends to insert the locking pin. The ends of the universal slide connectors are nearly identical, except one end must slide over the other.
The slide connector is similar to the universal slide connector and the quick connector except that there are two types of end connections. This is not a severe disadvantage, except that some planning may be required to assure compatible connectors are available and in place to be joined. The slotted tube connectors could present problems to a deployment crew if the boom is already in the water. If the sealed rope in the end of the boom is swollen, fouled, or the fabric is torn, it may be difficult to pull the rope ends into the slotted tube. Joining a boom with these connectors probably can only be done by two people working on land or on stable platform. The raised channel connectors have the same problems as the slotted tubes. These booms should be connected by two people working ashore. As in the case of the slotted tube, if there is no need to change boom length after it is deployed, a more elaborate and expensive version is probably not required.
Bolt connectors are likely to be firm and strong, but they should be manipulated ashore. Bolts are often used on booms that are permanently installed in harbors. They are very strong, so if there is no need to change the length of the boom after it has been deployed, they are adequate. Hinged plates and pin connectors can probably be installed by someone working over the side of boat in calm seas. The hinge probably can be joined easily, however installing the pin in the bottom of the boom that is already in the water could be a problem in rough weather. The hinge and pin connectors probably need two people for installation either ashore or on a fairly stable boat. These connectors are often used on booms permanently deployed in harbors. The hinges and pins are a strong connection and if the boom length does not require adjustment, the hinge and pin connectors are adequate.
Most of the quick connectors and slide connectors are made of marine aluminum. If the overall height of the boom is no more than about 24 inches, aluminum is satisfactory. However, for larger booms, a height of 36 inches or more, the connector may warp slightly making it almost impossible to join boom sections. As a result, these connectors are generally not used on large booms. Large open water boom sections are joined by bolt connectors or hinge and pin connectors made of stainless steel. This provides a strong secure connection. Boom sections can not be joined when the boom is in the water. Further, open water wind and wave conditions do not permit the joining of boom sections in any case.
In 1986, the American Society for Testing and Materials (ASTM) developed a standard hook neck for boom connectors, illustrated in FIG. 4. This standard was established to ensure booms from various sources would fit together without specifying how the connector must be made. FIG. 4 illustrates the approved ASTM end connector configuration. The standard specification is intended to provide for interconnectable oil spill response booms of various sizes, strengths, and designs and manufacturers. The design criteria calls for a hook engagement design. This is basically similar to the quick connector. The "Z" connector is to be secured with a self locking cross pin attached to each end of the boom by a lanyard long enough to reach a cross pin hole. A second pin is suggested for booms with an overall height of 24 inches. Further design criteria require that the connector shall have adequate mechanical strength, minimize oil leakage, have neither male nor female connections, be the full height of the boom of which it is a part, not impair stability of the boom, require no special tools for assembly, and not reduce freeboard. Other desirable features include speed and ease of connection, light weight, connectable in water, readily cleaned of sand and debris, inherently safe to personnel, and easy to install and replace.
Further, the end connector and cross pin materials shall be corrosion resistant in sea water and should have appropriate weight, mechanical strength, chemical resistance, flexibility, depending on the conditions in which it is to be used.
One improvement on the typical flat plate-bolted assembly illustrated in FIG. 3(g) is identified in U.S. Pat. No. 4,295,756. This end connector includes features of construction and arrangements of parts which provide for an improvement in load transfer between the connector and the fabric material utilized in the boom. This improvement in load transfer is achieved with a combination of elements and design features, all of which incorporate the use of flanges, bolts, rivets, and fasteners. One advantage of the '756 patent is that an extrusion with integral proximal end flanges negates the need to assemble two flat plates and connection is made as described specifically in FIGS. 2 and 3 of the subject patent via bolts, rivets, or other fasteners, (in particular, element 43 of FIG. 2), which securely clamp the connector flanges 35 to the boom fin fabric 38. As described in FIG. 2 of the '756 patent, elements 42, 48, and/or 53 are used to retain the fabric within the hollow cavity of the boom end connector. This connector assembly provides an advantage over the conventional flat plate connectors, wherein the flange connector can be utilized in a manner to increase the ability to transfer loads by other than simple friction between two flat plates.
The invention described in the present application is an improvement over the above-identified conventional boom end connectors. The present invention is directed to a novel, one-piece connector for use in oil spill containment boom systems. The present connector designed includes a special structural shape, which easily connects to the boom fabric and provides high tensile strength. This unique connector design utilizes a special extruded shape, which distributes the tensile loads in the curved walls of the connector in a manner which negates the need for proximal end flanges and in a manner which avoids the need for bolts, rivets, or other fasteners to secure the connector to the boom fin. Since the oil boom end connector of the present application negates the need for proximal end flanges, bolts, rivets, or other fasteners, oil booms utilizing the oil boom end connector of the present application require less assembly time and have a lower assembly cost.
This unique connector design further permits high speed, low cost fabrication, which may include high speed extrusion or injection molding. The size, simplicity, and form of the disclosed end connector are critical elements in reducing final boom assembly time, parts, maintenance, and overall cost.